A simple approach to obtaining enhanced mechanical properties of graphene/copper composites with heterogeneous grain structures

2021 ◽  
pp. 142438
Author(s):  
Liang Li ◽  
Longlong Dong ◽  
Wangtu Huo ◽  
Wei Zhang ◽  
Yue Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Simple Approach ◽  
Grain Structures

scholarly journals Sintering of Ti-based biomedical alloys with increased oxygen content from elemental powders

2020 ◽  
Vol 321 ◽  
pp. 05010
Author(s):  
J. Stráský ◽  
J. Kozlík ◽  
K. Bartha ◽  
D. Preisler ◽  
T. Chráska
Keyword(s):  
Mechanical Properties ◽  
Oxygen Content ◽  
High Strength ◽  
Simple Approach ◽  
Fine Tuning ◽  
Powder Metallurgy Method ◽  
Ti Alloys ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Low Modulus

Revived interest for beta Ti alloys with increased oxygen content is motivated by the prospect of achieving material with low modulus and high strength simultaneously. Fine tuning of amount of oxygen and beta stabilizing elements is critical for achieving good mechanical properties. This study shows that powder metallurgy method of spark plasma sintering is capable of producing Ti-Nb-Zr-O alloys from elemental powders. This simple approach allows for quick sampling and production of several alloys with various chemical composition. Elemental powders were mixed with appropriate amount of titanium dioxide to achieve Ti-29Nb-7Zr-0.7O alloy. Sintering was performed at 1400 - 1500 °C for 15 – 30 minutes.

Comparison of Microstructure and Mechanical Properties of Semi-Solid Castings Produced Using Billets Made by EMS and SEED

2014 ◽  
Vol 217-218 ◽  
pp. 332-339 ◽  
Author(s):  
Xiao Kang Liang ◽  
Da Quan Li ◽  
Pascal Côté ◽  
Stephen P. Midson ◽  
Qiang Zhu
Keyword(s):  
Mechanical Properties ◽  
Cross Section ◽  
Dendritic Structure ◽  
Casting Process ◽  
Grain Structure ◽  
High Quality ◽  
Microstructure And Mechanical Properties ◽  
Grain Structures ◽  
Heat Treated ◽  
Semi Solid

The spheroidal grains in billets used for semi-solid casting are generally manufactured by electromagnetic stirring (EMS) during the casting process. This method however, is not economically applicable for small quantities of the thixo billets. Swirled Enthalpy Equilibration Device (SEED) has been developed as a rheocasting process, and the SEED process is of interest for developing new thixo alloys, as well as for optimizing the thixocasting processes for high quality components. The objective of this paper is to compare the microstructure and mechanical properties of aluminum alloy 319s billets and castings produced using EMS and SEED feed materials. The experimental results show that for as-cast billets made from SEED process, a well-developed spheroidal grain structure is distributed throughout the cross-section of the billet, while for as-cast EMS billets, the grain structure is inhomogeneous, i.e., a dendritic structure was present adjacent to the surface of the billet, while a uniform, spheroidal structure was present at the centre. After the thixocasting process, however, the both SEED and EMS billets have well-developed, spheroidal grain structures. Mechanical properties of thixocast and T61 heat treated components are comparable for the both SEED and EMS billets.

Mechanical Properties of Hot-Pressed Silicon Nitride with Different Grain Structures

1979 ◽  
Vol 62 (1-2) ◽  
pp. 29-32 ◽  
Author(s):  
GUENTHER HIMSOLT ◽  
HEINRICH KNOCH ◽  
HEINZ HUEBNER ◽  
FRIEDRICH WILHELM KLEINLEIN
Keyword(s):  
Mechanical Properties ◽  
Silicon Nitride ◽  
Grain Structures

Friction Stir Processing (FSP) of Cast Metals: Microstructure – Property Relationships in NiAl Bronze and AA5083

2010 ◽  
Vol 638-642 ◽  
pp. 35-40
Author(s):  
Terry R. McNelley ◽  
Srinivasan Swaminathan ◽  
E. Sarath Menon ◽  
J.Q. Su
Keyword(s):  
Mechanical Properties ◽  
Ambient Temperature ◽  
Friction Stir Processing ◽  
Elevated Temperatures ◽  
Stir Zone ◽  
Friction Stir ◽  
Grain Structures ◽  
Microstructures And Mechanical Properties ◽  
Step Over ◽  
Equiaxed Grain

Parameters for multi-pass FSP include the pattern of tool traverse and step-over distance between successive passes. Multi-pass FSP was conducted on as-cast NiAl bronze and as-cast AA5083 in order to modify stir zone (SZ) microstructures and mechanical properties. Highly refined and homogeneous SZ microstructures may be produced by FSP. Refined and equiaxed grain structures reflect recrystallization during FSP; mechanisms leading to homogenization by redistribution of microstructure constituents remain to be determined. Refined microstructures exhibit enhanced ambient-temperature properties and superplasticity at elevated temperatures.

Normalizing, Annealing, and Spheroidizing Treatments; Ferrite/Pearlite and Spherical Carbides

2015 ◽  
pp. 277-291
Keyword(s):  
Mechanical Properties ◽  
Residual Stresses ◽  
Ferrite Matrix ◽  
Heat Treatments ◽  
Carbon Steels ◽  
Medium Carbon ◽  
Grain Structures ◽  
Medium Carbon Steels ◽  
Normalizing Annealing ◽  
Strength And Toughness

This chapter describes heat treatments that produce uniform grain structures, reduce residual stresses, and improve ductility and machinability. It also discusses spheroidizing treatments that improve strength and toughness by promoting dispersions of spherical carbides in a ferrite matrix. The chapter concludes with a brief discussion on the mechanical properties of ferrite/pearlite microstructures in medium-carbon steels.

Biaxial Tensile Deformation Behavior and Microstructural Evolutions of Superplasticity in AZ31 Magnesium Alloy

2007 ◽  
Vol 551-552 ◽  
pp. 225-230 ◽  
Author(s):  
M. Noda ◽  
Hideharu Shimizu ◽  
Kunio Funami ◽  
H. Mori
Keyword(s):  
Mechanical Properties ◽  
Grain Boundary ◽  
Tensile Deformation ◽  
Grain Boundary Slide ◽  
Mg Alloys ◽  
Biaxial Stress ◽  
Recrystallization Temperature ◽  
Boundary Separation ◽  
Biaxial Tensile ◽  
Grain Structures

Magnesium alloys show promise in meeting the demand for materials of lighter weight and higher rigidity. Mg alloys are hard to process and normally require grain refining for improved formability and mechanical properties. To process these fine-grained Mg alloys effectively, it is important to relate their load stress and mechanical properties to changes in their microstructures. Using a biaxial tensile machine and cruciform specimens, to evaluate the mechanical properties, microstructure, and plasticity, in a high temperature biaxial stress state, used of AZ31 Mg alloy sheet. With biaxial deformation, grain boundary slide occurred more frequently than with uniaxial deformation, causing grain boundary separation and formation of micro-voids between the grains. In the vicinity of the cracks and at the locations of grain boundary separation, although deformation temperature at higher than the recrystallization temperature, fine grains (about 2 )m) showing in duplex grain structures were formed locally. The formation of duplex grain structures as a result of local formation of fine grains during the deformation process is a major issue to be solved from the viewpoint of plasticity processing.

Analysis of AISI 1035 Grade Joints Welded Frictionally with Varying Forging Pressure

2014 ◽  
Vol 592-594 ◽  
pp. 63-66
Author(s):  
S.T. Selvamani ◽  
K. Umanath ◽  
K. Palanikumar ◽  
K. Vigneswar ◽  
Sudeep Kumar Ghosh
Keyword(s):  
Mechanical Properties ◽  
Carbon Steel ◽  
Fracture Surface ◽  
Tensile Properties ◽  
Metal Flow ◽  
Fracture Analysis ◽  
Medium Carbon Steel ◽  
Welding Parameter ◽  
Medium Carbon ◽  
Grain Structures

In this work we have satisfied the objective to analyse the medium carbon steel rods which are welded frictionally on their tensile properties when the welding parameter is maximum and minimum in values of forging pressure with respect to time. This work also carries the macrostructure and microstructure analysis of the weldments so as to identify the metal flow and grain structures in different zones of the welds. This work is carried to identify the suitable level of value of the forging pressure with respect to time and analysing their mechanical properties in that level. Fracture analysis was also carried out in the fracture surface.

Effect of Water Cooling on Grain Structures and General Mechanical Properties of 2219-T6 Friction Stir Welded Joint

2012 ◽  
Vol 706-709 ◽  
pp. 2986-2991
Author(s):  
Hui Jie Liu ◽  
H.J. Zhang ◽  
L. Yu
Keyword(s):  
Mechanical Properties ◽  
Mechanical Analysis ◽  
Water Cooling ◽  
Temperature Level ◽  
Friction Stir ◽  
Effect Of Water ◽  
Grain Structures ◽  
Joint Properties ◽  
External Water ◽  
Positive Effect

Regarding the friction stir welding (FSW) of heat–treatable aluminum alloys, although the thermal flow does not cause any material fusion, it can still deteriorate the local mechanical properties of the joints due to coarsening or dissolution of the strengthening precipitates. Therefore, it is of significance and possible to improve the joint properties by controlling the temperature level. For this purpose, a 2219-T6 aluminum alloy was underwater friction stir welded in the present study, and the temperature histories, grain structures and the general mechanical properties of the joints were investigated in order to illuminate the effect of water cooling. The results reveal that the water cooling action can effectively control the temperature level in the joint. The recrystallized grains in the weld nugget zone (WNZ) are significantly refined under the water cooling effect. The mechanical analysis indicates that the tensile strength of the joint can be improved by 6% through the external water cooling action. Additionally, the underwater joint also exhibits superior bend and impact properties to the normal joint, indicating the positive effect of water cooling on the general mechanical properties of the joints.

A comparison of continuous SPD processes for improving the mechanical properties of aluminum alloy 6111

2009 ◽  
Vol 24 (2) ◽  
pp. 459-469 ◽  
Author(s):  
R. Lapovok ◽  
L.S. Tóth ◽  
M. Winkler ◽  
S.L. Semiatin
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Friction Velocity ◽  
Asymmetric Rolling ◽  
Shear Texture ◽  
Angular Pressing ◽  
Grain Structures ◽  
Billet Material ◽  
Conventional Rolling ◽  
Aluminum Alloy 6111

Microstructure evolution, mechanical properties, formability, and texture development were determined for AA6111 samples processed by asymmetric rolling (ASR) with different roll friction, velocity, or diameters, conventional rolling (CR), and equal-channel-angular pressing (ECAP). Highly elongated or sheared grain structures were developed during ASR/CR and ECAP, respectively. ASR led to improved r-values and formability compared with CR primarily as a result of the development of moderate shear-texture components analogous to those developed during ECAP of billet material. ASR based on different roll diameters gave the best combination of strength, ductility, and formability.

scholarly journals Enhancement of Mechanical Properties and Rolling Formability in AZ91 Alloy by RD-ECAP Processing

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3503 ◽  
Author(s):  
Qiong Xu ◽  
Aibin Ma ◽  
Yuhua Li ◽  
Bassiouny Saleh ◽  
Yuchun Yuan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Shear Bands ◽  
Az91 Alloy ◽  
Ecap Processing ◽  
High Productivity ◽  
Fine Grained ◽  
Angular Pressing ◽  
Grain Structures ◽  
Large Numbers ◽  
Edge Cracking

In this study, the influence of rotary-die equal channel angular pressing (RD-ECAP) processing on the mechanical properties and rolling formability of AZ91 alloys was investigated. The as-cast and pre-homogenized AZ91 alloys were pre-processed by RD-ECAP for 16 passes at 573 K and subjected to post-ECAP rolling at 573 K with a rolling speed of 10 m/min. The microstructure and deformation characteristics of the AZ91 alloys were characterized. Results demonstrated that fine-grained AZ91 alloys with improved strength and ductility were obtained via the high-pass RD-ECAP processing, indicating a good plastic formability. The ECAP-ed alloys were easily rolled at 573 K from 4.5 mm to 1.1 mm in thickness without edge cracking. After rolling, heterogeneous grain structures were observed with large numbers of twins and shear bands that created strong basal textures. The rolled AZ91 alloys exhibited higher tensile strength and appropriate elongation. The post-ECAP rolling was successfully used in the high productivity of AZ91 rolled plates with good mechanical properties.

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